Will Mr Blair ever live up to the hopes of his political mentor?

It was typical of Lord Jenkins that he should have begun his last published words – only last week – with a quotation from John Updike. In his short foreword to a Britain in Europe pamphlet calling for British membership of the European single currency, he recalled that in the late Sixties the American novelist had described Britain as a "soggy little island huffing and puffing to keep up with Western Europe". He went on to argue with customary elegance that Britain had shaken off this pervasive image over the last 30 years largely through its membership of the European Union, and that many of these economic benefits were now at risk if the UK stayed out of the euro.

The point (for now) is not so much whether his analysis was right. It's arguable, for example, that he tended to underestimate the Thatcher economic reforms as another factor in the reverse of the decline noted by Updike. It's rather that it would be a disservice to his memory to assume, for all his genuine affection and admiration for Tony Blair, that he died yet sure that his legacy was intact.

Almost all the commentary – and most of the tributes – after his death has rightly emphasised his role as godfather to New Labour. In occupying, however temporarily, new territory beyond Labour's diminishing class base, the SDP pointed the way decisively to Labour's own future. Lord Healey's wonderful assessment of his old colleague in yesterday's Independent is nevertheless at least open to question when it blames the SDP split for Margaret Thatcher's success. She had already won her first victory, and the Labour leadership had been decided, when the split occurred. Moreover it's likely that with or without the SDP, Labour would have remained unelectable in 1983 or 1987.

That doesn't mean that New Labour is somehow perfectly Jenkinsite. The continuing surge in support, underlined in a new poll yesterday, for the Liberal Democrats, the party of which Lord Jenkins could unequivocally claim to be the architect, is evidence, is any were needed, that it isn't. Many in the Labour Party, still bitter over his 1981 apostasy, will be thankful for that. And yet the paradox is that many Labour Party members and supporters would be more comfortable with their party and its leader if it followed the Jenkins paradigm a little more closely.

Social liberalism is only part of it. Lord Irvine's commendable defence yesterday of the Lord Chief Justice's attempts to keep non-violent offenders out of prison, exhibited, in this Cabinet, an all too rare Jenkinsite willingness to face down right-wing clamour for retribution for its own sake. On war in Iraq, Lord Jenkins, a lifelong Atlanticist, but also part of a generation who had seen friends killed in the Second World War was closer to mainstream Labour than to Mr Blair. And even on electoral reform he held out the prospect of liberating politics from what Jenkins himself dismissively called the "lucubrations" of the focus groups. He was no great fan of unbridled privatisation. Beside all this, the intellectually coherent case for top-up fees he is supposed to have made is not as significant as his Labour critics make out.

That said, it's on the issue of Europe that Lord Jenkins had most suspended judgement on his part-protégé Tony Blair. In articles and interviews since the 2001 election he had urged Tony Blair to be bold on the euro, arguing that the Prime Minister's claim to be a great statesman rather than join the "long column of fudgers and sludgers" on Europe lay with whether he was prepared to risk a referendum on the euro in this Parliament. He was satisfied, on the basis of many talks with Blair, that he wanted to do just that. The question was whether he was prepared to face down the obstacles – including a possibly painful confrontation with Gordon Brown.

Jenkins was dismissive of the centrality conferred on the five economic tests, which he regarded as a "bit of a nonsense". Partly this was because of his own experience as Chancellor in the late Sixties when he had the greatest difficulty in persuading a deeply Eurosceptic Treasury to produce an objective cost-benefit analysis of joining the EEC, and when officials' obsessive concern about the negative impact of EU contributions on UK balance of payments were shown in hindsight to have been eclipsed by the economic benefits of vastly increased trade with Europe, once Britain had finally joined. But even without that experience it's hard to sign up to the notion of Dr Gordon Brown putting on his white coat, entering his laboratory in Great George Street, and establishing which colour the litmus paper turns in a liquid marked euro.

This isn't at all to say the economics don't matter or that a still stagnant German economy, much less a prohibitive exchange rate, may not argue for delay. But it is to say that even in favourable circumstances the sacredness of tests that cannot by definition foresee a "clear and unambiguous" benefit to the UK is highly questionable. It's wholly possible that the economic arguments will be finely balanced and that the political argument – assuming that Britain wants to stay in the EU and exercise influence within it – will in the pointed words last week of Patricia Hewitt, the Secretary of State for Trade and Industry, be "overwhelming".

Which means, as Jenkins saw, and Blair probably sees, that the decision will be much more political than the sanctity of the tests suggests. And that means that when the long-awaited discussion between Prime Minister and Chancellor takes place, the former may have to be highly political to get what he wants. On the one hand, as Jenkins foresaw publicly, it would be a blow to Blair's confidence if he does not have a referendum in the parliament and that could make his premiership vulnerable. But this could also cut another way. Whether it's true, as some say, that Jenkins thought Brown should have been moved in what he saw as the moment of Blair's "maximum power" immediately after the 2001 election, will probably never be known. But Brown's chances of succeeding Blair might be enhanced if a referendum did take place, since without it Blair might be inclined to insist on a third term. And if he achieved it, could Brown be confident of remaining as Chancellor, let alone of becoming Prime Minister?

The crunch could just be postponed for another year. If there is a protracted war in Iraq, it may be too late to focus governmental minds for the several months required to build an autumn referendum campaign. Tory weakness now means that a referendum in 2004 is not impossible. Jenkins, at any rate, was in little doubt that a willingness by Tony Blair to put Britain decisively at the heart of Europe was a key to whether he could claim greatness as a Prime Minister. This would not, perhaps, matter so much if it wasn't what Mr Blair almost certainly believes too. Mr Blair's tribute to Lord Jenkins on Sunday was graceful, unforced and deeply felt. But he knows that even in death, his great mentor's urgings will still resonate.

d.macintyre@independent.co.uk